Remove echoReplier

Mirror the ICMPv6 echo implementation in ICMPv4 echo. This removes
unnecessary asynchrony, reduces copying, and reduces complexity.

PiperOrigin-RevId: 240394525
Change-Id: If8f53254154f86772f5e51159765aa23b3b328b8

3 files changed, 11 insertions, 42 deletions

diff --git a/pkg/tcpip/network/ipv4/icmp.go b/pkg/tcpip/network/ipv4/icmp.go
index ea8392c98..7fd63c117 100644
--- a/pkg/tcpip/network/ipv4/icmp.go
+++ b/pkg/tcpip/network/ipv4/icmp.go
@@ -17,7 +17,6 @@ package ipv4
 import (
 	"encoding/binary"
 
-	"gvisor.googlesource.com/gvisor/pkg/tcpip"
 	"gvisor.googlesource.com/gvisor/pkg/tcpip/buffer"
 	"gvisor.googlesource.com/gvisor/pkg/tcpip/header"
 	"gvisor.googlesource.com/gvisor/pkg/tcpip/stack"
@@ -67,17 +66,17 @@ func (e *endpoint) handleICMP(r *stack.Route, netHeader buffer.View, vv buffer.V
 		if len(v) < header.ICMPv4EchoMinimumSize {
 			return
 		}
-		echoPayload := vv.ToView()
-		echoPayload.TrimFront(header.ICMPv4MinimumSize)
-		req := echoRequest{r: r.Clone(), v: echoPayload}
-		select {
-		case e.echoRequests <- req:
-		default:
-			req.r.Release()
-		}
 		// It's possible that a raw socket expects to receive this.
 		e.dispatcher.DeliverTransportPacket(r, header.ICMPv4ProtocolNumber, netHeader, vv)
 
+		vv.TrimFront(header.ICMPv4EchoMinimumSize)
+		hdr := buffer.NewPrependable(int(r.MaxHeaderLength()) + header.ICMPv4EchoMinimumSize)
+		pkt := header.ICMPv4(hdr.Prepend(header.ICMPv4EchoMinimumSize))
+		copy(pkt, h)
+		pkt.SetType(header.ICMPv4EchoReply)
+		pkt.SetChecksum(^header.Checksum(pkt, header.ChecksumVV(vv, 0)))
+		r.WritePacket(hdr, vv, header.ICMPv4ProtocolNumber, r.DefaultTTL())
+
 	case header.ICMPv4EchoReply:
 		if len(v) < header.ICMPv4EchoMinimumSize {
 			return
@@ -100,28 +99,3 @@ func (e *endpoint) handleICMP(r *stack.Route, netHeader buffer.View, vv buffer.V
 	}
 	// TODO: Handle other ICMP types.
 }
-
-type echoRequest struct {
-	r stack.Route
-	v buffer.View
-}
-
-func (e *endpoint) echoReplier() {
-	for req := range e.echoRequests {
-		sendPing4(&req.r, 0, req.v)
-		req.r.Release()
-	}
-}
-
-func sendPing4(r *stack.Route, code byte, data buffer.View) *tcpip.Error {
-	hdr := buffer.NewPrependable(header.ICMPv4EchoMinimumSize + int(r.MaxHeaderLength()))
-
-	icmpv4 := header.ICMPv4(hdr.Prepend(header.ICMPv4EchoMinimumSize))
-	icmpv4.SetType(header.ICMPv4EchoReply)
-	icmpv4.SetCode(code)
-	copy(icmpv4[header.ICMPv4MinimumSize:], data)
-	data = data[header.ICMPv4EchoMinimumSize-header.ICMPv4MinimumSize:]
-	icmpv4.SetChecksum(^header.Checksum(icmpv4, header.Checksum(data, 0)))
-
-	return r.WritePacket(hdr, data.ToVectorisedView(), header.ICMPv4ProtocolNumber, r.DefaultTTL())
-}
diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go
index 545684032..c2f9a1bcf 100644
--- a/pkg/tcpip/network/ipv4/ipv4.go
+++ b/pkg/tcpip/network/ipv4/ipv4.go
@@ -51,7 +51,6 @@ type endpoint struct {
 	id            stack.NetworkEndpointID
 	linkEP        stack.LinkEndpoint
 	dispatcher    stack.TransportDispatcher
-	echoRequests  chan echoRequest
 	fragmentation *fragmentation.Fragmentation
 }
 
@@ -62,12 +61,9 @@ func (p *protocol) NewEndpoint(nicid tcpip.NICID, addr tcpip.Address, linkAddrCa
 		id:            stack.NetworkEndpointID{LocalAddress: addr},
 		linkEP:        linkEP,
 		dispatcher:    dispatcher,
-		echoRequests:  make(chan echoRequest, 10),
 		fragmentation: fragmentation.NewFragmentation(fragmentation.HighFragThreshold, fragmentation.LowFragThreshold, fragmentation.DefaultReassembleTimeout),
 	}
 
-	go e.echoReplier()
-
 	return e, nil
 }
 
@@ -174,9 +170,7 @@ func (e *endpoint) HandlePacket(r *stack.Route, vv buffer.VectorisedView) {
 }
 
 // Close cleans up resources associated with the endpoint.
-func (e *endpoint) Close() {
-	close(e.echoRequests)
-}
+func (e *endpoint) Close() {}
 
 type protocol struct{}
 
diff --git a/pkg/tcpip/network/ipv6/icmp.go b/pkg/tcpip/network/ipv6/icmp.go
index e43253d3e..cfc05d9e1 100644
--- a/pkg/tcpip/network/ipv6/icmp.go
+++ b/pkg/tcpip/network/ipv6/icmp.go
@@ -136,8 +136,9 @@ func (e *endpoint) handleICMP(r *stack.Route, netHeader buffer.View, vv buffer.V
 		if len(v) < header.ICMPv6EchoMinimumSize {
 			return
 		}
+
 		vv.TrimFront(header.ICMPv6EchoMinimumSize)
-		hdr := buffer.NewPrependable(int(r.MaxHeaderLength()) + header.IPv6MinimumSize + header.ICMPv6EchoMinimumSize)
+		hdr := buffer.NewPrependable(int(r.MaxHeaderLength()) + header.ICMPv6EchoMinimumSize)
 		pkt := header.ICMPv6(hdr.Prepend(header.ICMPv6EchoMinimumSize))
 		copy(pkt, h)
 		pkt.SetType(header.ICMPv6EchoReply)